These don't work with the Rubi rock rails, but can replace them and provide a narrow step surface. I believe these are standard on the Moab version. I ordered a set from Amazon for my yet to be delivered JLU Sport S.
Well, since I'm new here, I can post a link yet but here's a description that you can search for.
Mopar 82215165AB Performance Rock Rails for 18-19 Jeep Wrangler Unlimited JL 4 Door